THE GLACIATION OF THE DINGLE PENINSULA
By V. BRUCE PROUDFOOT, B.A.
The Dingle Peninsula, as Dr. Farrington has pointed out,1
is of considerable importance in a study of the glaciation of
Southern Ireland, for it is part of the critical zone stretching
from Dingle Bay on the west coast to Dungarvan Bay on the
south where there appear to have been ice-free patches, even
during the maximum extent of glaciation.
In the map illustrating his paper on these unglaciated
areas in Southern Ireland Dr. Farrington has indicated that the
Dingle Peninsula, except for part of the northern coast, lies
beyond the southern limit of the end moraine of the Midland
General Glaciation. The peninsula also lies outside the
northern limit of the Greater Kerry-Cork Glaciation, which
runs in an easterly direction from Castlemaine.
Limited observations made near Dunquin suggest that
conditions'in this peninsular area during glacial times were not
as simple as would appear by merely considering the area to
have suffered corrie gladiation, for occurrences of ground
moraine have been observed along the western coast as at
Clogher, to the west of Croaghmarhin. It is apparent from the
Sheet Memoir of the area prepared by the officers of the
Geological Survey that the problems raised by this lowland
drift were rather complex.2 Du Noyer suggested that this drift
had been deposited by drift ice driven on the shore by strong
winds and currents. Whether this explanation was correct or
not he drew attention to the important point that striae and
other features were such that the direction of movement of the
ice which deposited these drifts was distinct from the direction
of movement of the corrie ice.
The term ground moraine, indicating drift deposited by
an ice-sheet or lobe from such a sheet, was used above deliberately, for there is no evidence to connect this drift with the
corrie glaciation. There is a wide altitudinal and lateral belt
quite free from drift of any sort. Absence of drift indicates
that piedmont ice masses
which occurred elsewhere during the
Kerry Local Glaciation3 were absent but this drift-free belt
may have had a snow or firn cover, this being, of course, quite
incapable of proof as there would be no deposits of any sort
from such a cover. The lowland drift has a patchy distribution
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along the coastal slopes of Croaghmarhin, reaching a height
above sea-level of about three hundred and fifty feet. In some
localities it is possible to differentiate between an upper fine
gravelly clay containing a certain amount of rock flour, and
a lower clay matrix of similar composition containing numerous
boulders. Whether there is any substantial time interval
between these two deposits is uncertain. It seems more likely,
however, that the different deposits merely betoken a minor
fluctuation in ice flow, rather than any major movement.
That such small movements took place is suggested by the
occurrence of soliflucted clays, sometimes solifiucted boulderclays, occasionally interbedded with more normal drift
deposits. The soliflucted boulder-clay conforms to the
description of such a deposit in the Glen of Aherlow, as given
by Dr. Farrington—rough stratification of the boulder-clay
without sorting, the long axes of boulders tending to lie
horizontally.4 Similar soliflucted boulder-clay also occurred
in a section exposed along the small river south of Dunquin,
between two stratified deposits interpreted as the result of
melt-waters coming down the valley from the mountains
where during a glacial or immediate post-glacial phase there
was probably a certain amount of snow on non-glaciated
slopes. Mention must also be made here of boulder-clay near
the coast which has been re-sorted by water action. The levels
at which this took place occur up to about one hundred feet
above present sea-level. Whether this re-sorting represents
marine action or the action of lake water ponded between the
land and a coastal lobe of ice is uncertain.
It would appear likely that the lowland drift was deposited
by coastal lobes of ice spreading beyond the major limits of
either the western phase of the Eastern General Glaciation or
Greater Kerry-Cork glaciations. Wherever deposits are seen
resting on solid rock there is no evidence that glacial action
was intense. Rather, these deposits seem to represent slowmoving depositional lobes of ice, doing nothing more than
re-deposit, virtually in situ, the pre-gla daily weathered
material, for there seems to be little, if any, carry-over of drift
from one rock type to another.
Unfortunately, it is quite impossible to relate this coastal
drift to the corrie glaciations of the mountains. All the high
level drift can be definitely associated with local corrie glaciers.
Conies occur not only on the north-east and north-facing
slopes of the Brandon-Stradbally mountain group, but also on
the south-west-facing slope of Brandon in the upper reaches
of the Feohanagh River, and on the north-eastern slopes of
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Mount Eagle. An important consideration with regard to these
corrie-deposited moraines is that there are instances, at least
on the south-western slope of Brandon, of considerable
accumulations of block scree, overlying the morainic deposits.
It is possible that this scree dates from the period when the ice
was no longer present in the southerly facing corries, but still
remained in the larger north-eastern corries.
Quite clean scree, totally distinct from hill wash, and in
many cases overlain by it, is widespread and presumably dates
from these glacial phases.
In conclusion, it is necessary to emphasize that although
the observations recorded above are of drift deposits on the
Dingle Peninsula, such deposits are of infrequent occurrence.
It has been suggested that a coastal lobe of ice was responsible
for the lowland drifts of the west coast and that corrie glaciers
account for all the high-level drifts. Even if these drifts be
contemporary there must always have been a broad area quite
ice-free between them. There is no evidence to suggest that
an ice-sheet covered the area at any stage of the glaciation.
1. Farrington, A.
1947
"Unglaciated Areas in Southern Ireland," Irish Geography, I, 91.
2. Jukes, J. B. and
Du Noyer, G. V.
Explanatory Memoir of Sheets 160, 161,
171 and part of 172 . . . illustrating part
of Co. Kerry. Dublin, 1863.
3. Charlesworth, J. K. 1928 "The Glacial Retreat from Central and
Southern Ireland." Quart. Journ. Geol.
Soc., 84, 302.
4. Farrington, A.
1945 " A Sketch of the Geological History of
the Glen of Aherlow. Irish Geography,
1, 43.
NOTE—-The material used in this paper was collected during the
Field Week of the Geography Department, Q.U.B. at Dunquin in
April, 1953. I am deeply indebted to Professor Evans for his interest
in this work and gratefully acknowledge the valuable help given by him
and by other members of the party, particularly Miss Harris, Mr.
Carleton and Mr. Johnson.
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